Ecdysteroids regulate molting in arthropods by binding to heterodimers of the ecdysone receptor and retinoid-X-receptor, homologous to the ultraspiracle protein, to induce the expression of downstream signal response genes including the nuclear receptor HR3. However, the detailed expression dynamics of HR3 during molting in spider mites are not yet clear. In this study, the full length of PcHR3 was retrieved based on the genome of citrus red mite, Panonychus citri. The open reading frame is 1707 bp encoding 568 amino acids, which contains a DNA binding domain and a ligand binding domain. Then, the expression pattern of PcHR3 was analyzed throughout the development of the deutonymph by RT-qPCR. The result showed that PcHR3 was mainly transcribed in the late deutonymph stage, when the deutonymph was at least 24 h old and motionless, the critical point at which the mites started molting. Transcription reached the highest level in 32-h-old deutonymphs and decreased by 36 h, where the mites remained in a quiescent state. Further silencing of PcHR3 by leaf-disc-based delivery of dsRNA to 8-h-old deutonymph mites, resulted in retarded development and death of 58% of deutonymphs. In summary, we suggest that PcHR3 regulates the latter stages of molting in P. citri.

中文翻译：

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核受体HR3的RNAi提示其在红蜘蛛Panonychus citri的蜕皮过程中起作用。

蜕皮类固醇通过与蜕皮激素受体和类维生素A-X-受体的异二聚体结合来调节节肢动物的蜕皮，该异源二聚体与超微血管蛋白同源，从而诱导下游信号响应基因的表达，包括核受体HR3。但是，HR3在红蜘蛛蜕皮过程中的详细表达动态尚不清楚。在这项研究中，基于柑橘红螨Panonychus citri的基因组检索了PcHR3的全长。开放阅读框为1707bp，编码568个氨基酸，其包含DNA结合结构域和配体结合结构域。然后，PcHR3的表达模式通过RT-qPCR在整个反义词开发过程中进行了分析。结果表明，PcHR3主要在氘代末期转录，此时氘代至少24 h且静止不动，这是螨开始蜕皮的临界点。转录在32小时的德国人中达到最高水平，并在36小时内减少，此时螨虫保持静止状态。通过将基于叶圆盘的dsRNA传递至8小时龄的亚特兰大螨，进一步使PcHR3沉默，导致58％的亚特兰大发育迟缓和死亡。总而言之，我们建议PcHR3调节柑桔体育蜕皮的后期阶段。